Using similar load data when that’s all you’ve got

[GymB]

Prefer not to blow my face off, not even half of it.

Gun is a Handi Rifle, 357 mag, 16” barrel, need to measure twist tomorrow but published is 1:15.5

Using .357mag brass, small pistol primer and Vihta Vuori N110 powder. Bullet is a Speer 200gr TTSX-BT.

Vihta Vuori provides load data for a Speer 200g TMJ (max 12.8g of N110, start 12.2). Starting load delivers 1,180 FPS from a 7” barrel, I want to stay close to 1,000 FPS.

My chamber will allow me to load these out past 2.135” so I will have at least as much available volume in the case as the published load. Finished round is about the length of a 200gr 300BLK round and has about the same case capacity, just a bit more girth.

I believe that I can use the published data because I have not changed either bullet mass or available case volume, just the bullet profile and there is adequate room for the profile in the leade. Plan to start under the suggested starting load to stay subsonic. Anyone see a problem?

Now it gets tricky, stepping up to 220gr SP. Again I can load it long enough to maintain case capacity, but I have no data for this mass. Thinking drop back to 1.5g or 2.0g less than what I end up with for the 200g bullet and be prepared for a squib, work up from there.

Considered trimming some 357max brass back to 1.3” and using it instead of the 357mag brass because the web is more robust. This will change capacity, so I’d have to measure that and adjust, and it’s also significantly more expensive. I’d like to stay with the 357mag brass for now.

Am I missing anything? Have any ideas or concerns.

 

[Toprudder]

I don't know if the brass is the limiting factor on pressure (I suspect it is not) so I don't see the advantage of going with the 357max brass and trimming it down. In fact, for the same amount of powder, but less case volume, you will have higher pressure. But, since you are trying for subsonic and lower velocity, you might actually be better off using a smaller volume case to get a more complete burn of a low charge.

If N-110 starting loads result in 1180 fps from a 7" barrel, and you want 1000 fps from a longer barrel, that means you will have to start even lower. Some powders don't like to be downloaded, and most sources say not to go more than 10% below max charges. Also, when you go significantly below starting charges, you start to get incomplete burning of the powders due to the lower pressure, and you also won't get enough expansion of the brass to get a good gas seal. I think you will be better served by a faster burning powder. But, you will need one that gives good case fill (like Trailboss) or one that is not position sensitive (BE86, Clays, and Titegroup). And then you have to be very careful while testing to insure that you don't stick a bullet in the barrel from a low charge.

There are manuals that have 357mag rifle load data, such as Hornady, Speer, and Lyman. I would start there. I would stay away from H110/W296 as they are known not to like being downloaded.

 

[BowWow]

I'd say you'd be safe to try 10 grains (or maybe slightly less) and go from there. You usually have to load wayyyyy down to get a squib.....like less than 5 grains with what you're using. I've played "Limbo" reloading with Bullseye and a 148gr wadcutter. I was down to 1.7 grains or so of powder and the bullet still made it out of a 6 inch barrel. I don't remember the exact velocity but it just under 400fps IIRC......and much quieter.

While we're at it....if your goal is to be subsonic, Use 38 special reloading data. I load most of my 357 brass down to 38 special specs for range purposes. I have a different box of brass for magnum loads.

 

[Catfish]

I checked all my books and internet sources for 357 mag rifle heavy subs and came up dry. They all top out at 170-180 gn bullets. It sounds like you’ll be going off book if you follow through on this.

Here is a discussion that might be helpful:
http://www.silencertalk.com/forum/viewtopic.php?t=102514

 

[GymB]

for the same amount of powder, but less case volume, you will have higher pressure

Actually am able to load long and maintain case capacity. Otherwise I’d be worried because we really don’t know what the pressure curves look like with materially reduced case capacity.

I do have a bunch of trailboss, thanks for the idea I’ll plan to try that. I have lots of faster powders, like titegroup, but am concerned about the pressure curve with a bullet over max mass. My sense is that I’ll be better of pushing for the length of the barrel than having a big pressure spike up front.

 

[GymB]

Use 38 special reloading data.

I’ll look, but assumed that there isn’t any such data for a 220-220 g bullet. Would make sense to load with less case capacity if that is an option, would likely give better burn as @Toprudder mentioned.

 

[Toprudder]

I forgot to mention, use a tight crimp if you use the slower powders. You obviously don't need it for bullet jump or setback, but it will help getting a more complete ignition and burn.

 

[Toprudder]

I do have a bunch of trailboss, thanks for the idea I’ll plan to try that. I have lots of faster powders, like titegroup, but am concerned about the pressure curve with a bullet over max mass. My sense is that I’ll be better of pushing for the length of the barrel than having a big pressure spike up front.

That is the nice thing about Trailboss, as long as you fill the case up and don't compress it, you are safe.

 

[Slacker]

Tagged for when I get to my notes.
I made a thread on the other board using 35 Rem boolits 200-220gr, in 38spl brass
In my 357 handi and Rooga 77/357.

As I recall, Lil gun powder was the overall winner for SD & accuracy.
It excells in heavy for caliber uses.

 

[Toprudder]

Tagged for when I get to my notes.
I made a thread on the other board using 35 Rem boolits 200-220gr, in 38spl brass
In my 357 handi and Rooga 77/357.

As I recall, Lil gun powder was the overall winner for SD & accuracy.
It excells in heavy for caliber uses.

Were you loading for subsonic, though?

 

[Slacker]

Where you loading for subsonic, though?

Yes.
I'd be skittish of pushing a .358 Speer 225gr deep curl PSP above 1050fps in a .357 mag platform...although the handi is a tank and would probably just lock up.

Although, as I recall, no pressure signs were evident @ 1050fps.
I have pics somewhere.

(Mr. Boat was not impressed with my "off the reservation" loading)

Lil gun is an awsome powder. Very forgiving of heavy for caliber use and it has always surprised me with the accuracy it gave.

I gotta go over to Canada to find the thread.

 

[Slacker]

220gr Speer in 38spl brass.
Aka, straight wall 300 blackout.

9.5gr lil gun. I was limited in COAL by the rooga mag. Not an issue in the handi.
If I recall correctly, this have me 1050fps in 16" barrel and 1027fps in a 7" barrel, same gun, before and after barrel chop.

Very cool to lob these at steel.
It really rings the gong.
Folks who are used to 556 type bullets laugh out loud when this hits a steel plate.
It swings the plate and sounds like a tibetan monk ringing the bell on a mountain top.

 

[GymB]

@Slacker welcome back from your brief trip to Canada.

I am holding off on loading these in the 77/357, and for testing have put the handi barrel on a heat-treated receiver so nothing should break so long as I stay reasonable.

Thanks for sharing your load data, but so much for using up my N110!

Plan is to take these up to MI on a family trip. The family up there shoots steel with unsuppressed 223, I expect this and the 300blk to be a lot of fun suppressed.